The present invention relates, in general, to a machine having a basic body and a machine element which is movable relative to the basic body by an electric working drive.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Movable machine elements in machines are normally driven by means of electric motors (electric working drives). In many cases, the electric motors need to perform highly dynamic movements for this. During acceleration and braking of the movement, large current spikes occur. Normally, the current spikes are taken directly from the supply system supplying power to the respective drive and are returned to the system by generator. This practice causes high load levels on the supply system. In addition, the high peak current requirement means that the electric infrastructure, such as supply lines, fuses, contactors, transformers, etc., needs to be appropriately dimensioned, so that it can cope with the peak current requirement.
Machines with a high peak current demand normally do not require special measures to be taken in order to lower the current spikes on the supply system. In individual cases, however, it is known to additionally provide a further electric drive (electric buffer drive) which has a flywheel connected to it. The presence of the flywheel means necessitate considerable safety precautions. In particular, it is necessary to ensure that a dangerous state does not occur even if the flywheel detaches from the buffer drive. In addition, the flywheel needs to be counterbalanced with a high level of accuracy. Otherwise, there will very quickly be bearing wear in the buffer drive.
It would therefore be desirable and advantageous to provide an improved machine which obviates prior art shortcomings and which is simple in structure and yet reliable in operation.